selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/virt/kvm/Makefile.kvm b/virt/kvm/Makefile.kvm
new file mode 100644
index 000000000..d047d4cf5
--- /dev/null
+++ b/virt/kvm/Makefile.kvm
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for Kernel-based Virtual Machine module
+#
+
+KVM ?= ../../../virt/kvm
+
+kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
+kvm-$(CONFIG_KVM_VFIO) += $(KVM)/vfio.o
+kvm-$(CONFIG_KVM_MMIO) += $(KVM)/coalesced_mmio.o
+kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o
+kvm-$(CONFIG_HAVE_KVM_IRQ_ROUTING) += $(KVM)/irqchip.o
+kvm-$(CONFIG_HAVE_KVM_DIRTY_RING) += $(KVM)/dirty_ring.o
+kvm-$(CONFIG_HAVE_KVM_PFNCACHE) += $(KVM)/pfncache.o
+kvm-$(CONFIG_KVM_GUEST_MEMFD) += $(KVM)/guest_memfd.o